The present invention relates to devices and methods for applying threads on supports, particularly supports of plastic or rubber material, said devices and methods making it possible, for instance, to produce reinforcement plies, in particular reinforcement plies for tires. The invention relates, in particular, to methods and devices which make it possible to apply threads on a support imparting them a sinuous shape.
Devices which make it possible to apply threads on a support while giving them a sinuous shape are described, for instance, in the following patents or patent applications: FR 2 042 859, FR 2 325 497, FR 2 501 126, SU 704 816, WO 81/1151.
These devices have at least one of the following drawbacks:
complicated nature of the devices resulting in frequent breakdowns or requiring costly and frequent maintenance; PA1 lack of precision in the placement of the threads so that the plies obtained have a heterogenous geometry and, therefore, physical properties which differ along their length. PA1 a) a drum is used which is caused to turn around an axis; PA1 b) the drum comprises rows of teeth, each row being parallel to the axis of rotation of the drum and the rows all having the same number of teeth; PA1 c) every second row is such that its teeth are fixed, the other rows being such that their teeth are movable, in a direction parallel to the axis of rotation of the drum; PA1 d) the threads are brought into contact with the drum at a place where the fixed and movable teeth are substantially aligned in planes perpendicular to the axis of rotation of the drum, these planes being the same for the fixed teeth and the movable teeth, the threads being arranged parallel to said planes between pairs of teeth in the rows of fixed or movable teeth; PA1 e) the threads are carried along by the rotation of the drum and the movable teeth are displaced, they, in turn, displacing the threads in contact with them so as to impart a sinuous shape to the threads on the drum; PA1 f) the support is brought into contact with the drum and the threads at a place where the threads have substantially acquired their final sinuous shape on the drum; PA1 g) the ply formed by the support and the threads in contact with the support is removed from the drum. PA1 a) it comprises a drum with means, referred to as "means of rotation", which make it possible to drive the drum in rotation around an axis; PA1 b) the drum comprises rows of teeth, each row being parallel to the axis of rotation of the drum, the rolls all having the same number of teeth; PA1 c) every second row is such that its teeth are fixed, the other rows being such that their teeth are movable and the device comprises means, referred to as "displacement means," which make it possible to displace the movable teeth of said other rows parallel to the axis of rotation of the drum; PA1 d) the device comprises means which make it possible to cause the thread to come into contact with the drum at a place where the fixed and movable teeth are aligned substantially in planes perpendicular to the axis of rotation of the drum, these planes being the same for the fixed teeth and the movable teeth, the threads being arranged parallel to said planes between pairs of teeth in the rows of fixed or movable teeth; PA1 e) the means of rotation and the displacement means are so arranged that the threads are driven along by the rotation of the drum and that the movable teeth are displaced, in their turn displacing the threads in contact with them so as to impart a sinuous shape to the threads on the drum; PA1 f) the device comprises means which make it possible to cause the support to come into contact with the drum and the threads at a place where the threads have substantially acquired their final sinuous shape on the drum; PA1 g) the device comprises means which make it possible to remove from the drum the ply formed of the support and the threads in contact with the support.
EP Application A 318 791 describes a device for applying threads on a support using two pincers, a front pincer and a rear pincer as seen in the direction of advance of the support and of the threads, the device comprising means which make it possible to open and close the pincers, and means which make it possible to displace the rear pincer along the direction of advance or along a direction opposite the direction of advance, as well as means for displacing the threads in transverse directions. The device described in this application EP-A 318 791 makes it possible to deposit the threads with great precision, but the speed of deposition is relatively slow as a result of the complicated succession of movements of the pincers which make it necessary to stop the support upon transverse movements of the threads before they are applied to the support and upon the application of the threads to the support.
The object of the present invention is to overcome these drawbacks.